The temperature difference between them shouldn't be noticeable as long as your buy a good aftermarket cooler.
The 7970 is more of a contender with the 680/770, so unless you plan on a dual-card config in the future, then go for the 7970. However, the 7970 is similarly priced to the new GTX 770, which outperform the 7970. I would go with the 770
I'd say a 7970 (specially the GHZ) and yes there might be small bottleneck with your current cpu but it's not that big to make you play worse. but I do agre the 770 is a better option but if you can't afford going both gpu + cpu + mobo (if you go to the i5) then I suggest enjoy the 7970/770 and just upgrade a few months later specially if you own a lower level gpu.
Yeah i need help with choosing a GPU it between a GTX 670 and Radeon 7970 ive been told and read that a 7970 runs very hot which is why i carnt choose but also been told it very good when overclocking
The 7970 is better, hands down! It even beats the GTX 680 and judging by what tomshardware says: http://www.tomshardware.com/reviews/gaming-graphics-car... , HD 7970 GHz is on one level with GTX 780, GTX 590 and HD 6990 which are way, way above what GTX 670 can ever dream of. In the list, you can find that GTX 670 has similar performance to HD 7870 XT, so you mustn't think any farther, just grab yourself a 7970 or a 7970 GHz and you can be 100% sure that what you've chosen is better than GTX 670.